DIAGNOSIS AND MANAGEMENT OF AMBLYOPIA.pptx

Management

1. MANAGEMENT OF AMBLYOPIA DR. FASHOLA M.B.

2. Outline Introduction Epidemiology Aetiology Pathophysiology Classification Assessment Management ATS Follow up References

3. Introduction Amblyopia is the unilateral, or rarely bilateral decrease in best corrected visual acuity (BCVA) for which there is no identifiable pathology of the eye or visual pathway. It can result from form vision deprivation and/or abnormal binocular interaction in the sensitive period of development. Clinically, can be defined as a difference in BCVA of 2/more lines (or >1log unit)between the two eyes, in the absence of organic lesion.

4. Introduction… It signifies a failure of normal neural development in the immature visual system. The visual system is most sensitive in the first 2years of life, and may be modified by quantity or quality of visual input. [Critical period] The critical period ends at around 7 – 9years of age Failure to diagnose and manage amblyopia before the age of 8 years can result in life-long visual impairment.

5. Epidemiology Variable, WHO estimates global prevalence of 1.0 - 5.0%. 19million children <15 years of age are visually impaired, 12 million of these are impaired due to uncorrected refractive errors and amblyopia. Preschool/School age children: 4.0 – 5.3% No sex predilection.

6. Epidemiology… Prevalence in Nigeria (school-based studies): 0.1 – 3.1%. No significant age or sex predilection. Refractive amblyopia most common. Multi-ethnic paediatric eye disease study (MEPEDS): Varies with ethnicity. Refractive amblyopia (75%) > Strabismic > Form deprivation. Anisometropia was the commonest cause of refractive amblyopia.

7. Epidemiology… Risk factors 4 times more prevalent in preterm and LBW. 6 times more prevalent in CNS disorders & delayed milestones. Smoking and alcohol intake in pregnancy are risk factors for development of amblyopia.

8. Aetiology Visual Deprivation Monocular: Strabismus, Anisometropia. Binocular: Bil . High refractive errors. Light Deprivation Monocular: Unilateral mature cataract, Unilateral corneal opacity, Ptosis. Binocular: Bilateral mature cataract. Abnormal Binocular Interaction Strabismus, Anisometropia.

9. Pathophysiology Described by Wiesel and Hubel in the 1960s. Their research showed that in infant animals visual stimulation with a blurred retinal image resulted in loss of nuclear cells in the LGN, the first relay nucleus of the visual system.

10. Pathophysiology… Normally, there are 6 nuclear layers of the LGN—3 layers corresponding to the RE and 3 layers corresponding to the LE. A unilateral blurred retinal image destroys the 3 nuclear layers of the eye with the blurred image. Because of the increased visual stimulation from the clear image, the 3 layers corresponding to the clear image eye are darker stained and larger than normal. Ocular dominance columns in the visual cortex are also damaged by a unilateral blurred image during early development.

11. Pathophysiology…

12. Classification/Types Strabismic Amblyopia Stimulus deprivation Amblyopia/Amblyopia of disuse Anisometropic Amblyopia Bilateral Ametropic/ Isometropic Amblyopia Meridional Amblyopia Organic Amblyopia

13. Strabismic Amblyopia A common form of amblyopia, occurring in 40% of children with manifest squint (>8PD in straight gaze). AbN binocular interaction & Suppression of deviating eye, Unilateral. Esotropia > Exotropia. Rarely in hypertropia.

14. Stimulus Deprivation/Amblyopia of Disuse Lack of adequate visual stimulus on account of visual axis obstruction from: Congenital/Early developmental cataract Moderate – Severe Ptosis Corneal opacity Vitreous haemorrhage/opacity Unilateral/Bilateral

15. Bilateral Ametropic/ Isometropic Amblyopia Bilateral ametropia occurring on account of significant uncorrected refractive error, especially hypermetropia. Hypermetropia of >+5D; Myopia of > -8D; Astigmatism of >2D (Meridional Amblyopia): image blur in one meridian, can be unilateral or bilateral.

16. Anisometropic Amblyopia Caused by asymmetric refractive error between the two eyes, causing image suppression in the eye with the larger error. Difference of >/= +1.00D in hypermetropia >/= -3D in myopia >/= 1.50D of astigmatism.

17. Assessment History General Examination Ocular examination Visual acuity: Objection to occlusion of one eye/Preferential looking Unilateral – BCVA difference between the two eyes of >/=2 lines (1 Logmar ). Bilateral - <6/9 in a child 5years and older. <6/12 in a child 4-5years old <6/15 in a child </=3years old.

18. Assessment… Note: Crowding phenomenon: Single optotypes Vs Line optotypes Vs Single optotypes with crowding bars.

19. Assessment Colour vision tests: abN in amblyopic eyes. Tests for binocularity/Stereoacuity: Titmus fly test, Two pencil test, Worth 4-dot test, Maddox rod test. Contrast sensitivity testing. Ocular alignment and motility. Lid – Ptosis. Conjunctiva.

20. Assessment… Cornea: Opacity A/C: Deep/Shallow Pupil: Some studies reported anisocoria with pupil in the amblyopic eye being 0.5mm larger. APD has also been reported in some studies. Lens: Cataract

21. Assessment Fundus: Assess red reflex in both eyes; Look for pathologies that may account for visual loss. Electroretinogram Electro-oculogram Visually evoked potential: Reduction in amplitude &slightly prolonged latency.

22. Assessment… Neutral density filter test. Cycloplegic retinoscopy/Refraction. Ocular B scan.

23. Management Early detection via Screening programs. Goal of Treatment Normalize V/A in affected eye while maintaining normal vision in other eye.

24. Management… Principles Counselling; Eliminate visual axis obstruction; Correct any significant refractive error; Force use of the amblyopic eye by limiting use of the other eye.

25. Management… Force use of Amblyopic Eye Occlusion of normal eye, by patching: Part-time: Occlusion for 2 – 6hours per day. Full time: Occlusion during all waking hours. Choice is dependent on age of patient and density of amblyopia.

26. Management… 2. Penalization with Atropine Used when compliance with patching is poor. Vision in the normal eye is blurred with use of atropine. Best in relatively mild amblyopia. 3. Optical Penalization – altering the optical correction of normal eye to produce image blur. 4. Others: Temporary tarsorrhaphy, Botulinum toxin to levator muscle.

27. Management… Mild to moderate Strabismic &/or Anisometropic Optical correction of any significant refractive error Patching for 2-4 hours/day or Atropine Further management of strabismus More aggressive patching for residual amblyopia

28. Management… Severe Strabismic &/or Anisometropic Amblyopia Optical correction of any significant refractive error Plus: Patching (6 hours) or Atropine (weekend-only or two consecutive days) Further management of strabismus Bilateral ametropic amblyopia Optical correction

29. Management… Stimulus deprivation amblyopia Early surgery Early post-op patching Stimulus deprivation amblyopia with concurrent non-form deprivation amblyopia Early surgery Optical correction ± Patching or Penalization

30. Amblyopia Treatment Study (ATS) Paediatric Eye Disease Investigator Group (PEDIG)

31. ATS..

32. Management…Active Pleoptics : Used for active stimulation of the fovea. The peripheral retina is exposed to intense light, after the light source is turned off, the fovea functions better. The fovea can then be directly stimulated directly by a pleoptophore ( Bangerlers method) .or indirectly by producing after images (Cupper’s method)

33. Management..Active Treatment using grating stimuli (using CAM vision stimulator): Amblyopic eye is stimulated for 7mins by slowly rotating high contrast square wave grating of differential spatial frequencies. The rotating gratings are thought to provide cortical stimulation. Done once a week for 3 – 4weeks.

34. Management…Active Perceptual learning: involves repeatedly practicing a visual discrimination task e.g. contrast sensitivity, stereo-acuity etc. Done 2hrs/day, 5days/week, for 9months. Video Game playing : Pushes brain function to its limit, enabling the amblyopic visual system to learn, recalibrate and adjust. Binocular stimulation : viz penalization.

35. Management…Active Monocular fixation in a binocular field (MFBF) : Presentation of peripheral stimulation to both eyes and stimulating only the fovea of the amblyopic eye. Interactive binocular Treatment of Amblyopia (I- BiT TM ) : Present separate images to both eyes, preferentially stimulating the amblyopic eye. Makes use of shutter glasses, HD screens.

36. Management…Active Software-base active treatments of Amblyopia (home or office use): AmbP iNet program: Treatment involves visual search of certain things. Designed to improve hand-eye coordination, VA, crowding effect and visual memory. Exposure to darkness. Pharmacological therapy: Levodopa (ATS 17A), Catecholamines. Near activities.

37. Complications of therapy Failure of therapy Reverse Amblyopia Atropine toxicity

38. Follow-up In stimulus deprivation amblyopia post-cataract surgery, 1 day, 1 week, and 1 month post-op visit. Thereafter, monthly or bimonthly visits allow for aggressive treatment of amblyopia and monitoring for changes in refraction. Once visual acuity in the amblyopic eye has stabilized over 2 to 3 visits, treatment can be tapered.

39. Follow-up… Maintenance patching of 1–2 hours per day is often prescribed to prevent recurrence of amblyopia after successful patching. Primary therapy should generally be terminated if there is a lack of demonstrable progress over 3–6 months despite good treatment adherence.

40. Follow-up Many amblyopic children will be left with a residual visual deficit despite compliance with treatment, especially those starting treatment at an older age; those with severe amblyopia; and those with form-deprivation amblyopia;

41. References Megbelayin EO 1 . Prevalence of amblyopia among secondary school students in Calabar, south-south Nigeria. Pediatric Ophthalmology and Strabismus. American Academy of Ophthalmology. Basic and Clinical Science Course. 2016-2017. JJ Kanski. Clinical Ophthalmology. A Systematic Approach. Eighth Edition Elsevier Butterworth Heinemann. London 2007 AK Khurana. Comprehensive Ophthalmology. Fourth Edition. New Age Publisher. New Delhi 2007. Management of Amblyopia, Eyewiki .